Topic: April 21 to April 24 2007 Tornadoes - Tornado Alley

[Jimmy Deguara]

Hi,

A short wave is expected to pass over the Texas panhandle today with primary concerns of large hail and tornadoes! The storms will quickly develop into line segments and possibly bow echos after the first discrete supercell behaviour. I like the upper level lapse rates as well as the very unstable soundings! 700 to 500 temps are of the order of 23 to 24C! We struggle in Australia to get 19C.

Watch this system unfold at the Storm Prediction Center http://www.spc.noaa.gov

Warnings are on the National Weather Service    http://www.nws.noaa.gov

I am based in Amarillo and expected to target storms developing south of I-40 but I could end up very far south!

Regards,

Jimmy Deguara

[Michael Thompson]

Situation appears to be coming together right now (9:00am Australia East ),  (6.00pm Central Plains ).

A line of storms stretches from South Dakota to the Texas panhandle.

The storm in the Texas panhandle is labeled by SPC as 'Particularly Dangerous "

Radar shows that if Jimmy is Amarillo he will be on to something now or soon, a storm just SW of Amarillo has gone tornado warned.

What I like about this storm is that it is sitting on the southern edge of an obvious gap in the line ( along the dryline ). This gives it a bit more isolation, especially on the SE flank, and it should therefore build better.

[David C]

There are a lot of precip cores evident so you would have to a rapid transition to squall line even   south of Amarillo. Really need these storms to remain discrete for the next few hours -- and the storm heading towards Plainview would be the best bet in my oppininion. Expect tornado warning shortly.

[nzstorm]

Yes, forming into a long squall line quickly.

I see a tornado reported in SE Colorado.

[David C]

There were tornado warnings out of Nebraska too Steve so widespread action!

Tornado damage reported from the storm near Plainview - unless the warning was not updated on the page that  I was viewing, there was a hook and intense couplet evident on radar prior to the t-warning being issued. This storm at least has 'unimpeded' inflow and is in good position to head east into an increasingly more favourable kinematic and thermodynamic enviornment - definitely one to watch. I've not been able to conact Jimmy on the cell phone so no idea which storm he is on.

[James]

Hoping JD managed to score a few today. Some of the pictures and reports coming out are brilliant including this time lapse which I personally feel is one of the best videos I have ever seen in showing Supercell/Tornado dynamics.

http://www.atmo.ttu.edu/walter/Storms.html

About half way through the video, as the rain clears revealing the meso, you can see the sudden increase in moisture from the left as the inflow thickens up substantially. Watching the meso increase in size during the next few seconds/video position changes is brilliant as well as the rotating wall cloud and resulting tornadoes. I love seeing actual storm structure like this in time lapse. You can really feel and see what is going on inside the storm.

[Jimmy Deguara]

Hi guys,

I am back online. Reading what I see above, I would hate to disappoint any of you that were expecting a few tornadoes or countless as some have stated. This was a difficult chase for anyone that would have chased - though those that were in a team had advantages as well as those with the data access. Not to discount the tornado that passed right over chasers in Tulia! Experienced chasers too! I guess when you consider navigating, filming, taking photographs, checking radar data on Baron WX - I was chasing solo. No updates. Then you get the perspective. The storm as depicted below was moving at 60 miles per hour and then slowed to about 45 miles/hr. There were people near the tornadoes and missing them all! The plan of attack had to be precise or you missed the boat!

I started out near Hereford (from Amarillo) but with the feeling not much was happening and the dryline was pushing through, I headed north for the NW panhandle near Dalhart and a cell developed off the dryline. I took this storm because I didn't want to be in a position where storms erupted late. There was no doubt storms would develop further south. David may recall 15th May 2003 when we hung around Amarillo - some were comparing this with that event! Very edgy on this day haha.

Anyway I continued on with this storm and even doing the speed limit it neared me slowly but remained west of me! It was heading rapidly NNE. What was amazing was it looked crappy and high based but once it hit moisture near Springfield Colorado yes Colorado it rapidly intensified. And what I saw was a storm rapidly organising as I moved north and was on the W side. The storm was spitting lots of hail at this point nickel sized. The hail curtain was already forming a hook! and the bases were lowering! Altitude in this region is 1200-1300m

I finally found a way of getting E via Lamar - eventually passed through hail missiles - I would say 4 to 5cm in diameter! The transition was incredible - inflow bands! The storm was already tornado warned within 30 minutes after hitting moisture - that shows how incredible the shear was on this day.

I finally got to Granada, CO and filmed timelapse of this supercell - rapidly developing structure! This storm to my knowledge although rapid rotation on radar did not produce a tornado. It was the second one further south that had exploded whilst travelling north was the storm. It approached half hour or so later and became dominant. I began to realise that with each cell, although the winds were from the S to SE, the storms were dragging winds from the E but in this case as I moved into position in view of the notch - the winds were from the ENE to NE! Storm relative flow!

I had observed a rainfree base in the distance but the next thing I saw was a large wedge tornado! The storm scale rotation was of the order of other supercells producing strong to violent tornadoes I had observed in the past! Forget about timelapse this rotation was easily viewable and at wide diameter from the centre of rotation. Within seconds the storm dragged rain from the SE side right around!

I have been contacted by the NWS about this particular tornado given very few covered it. The radar signature for this storm at this time was "through the roof"! My first Colorado tornado and it was a wedge! To say I am more than satisfied is an understatement - I have not seen a wedge since 2001 - the famous White Deer tornado.

Anyway, I am going to try placing the view online at some point once I have passed the information they required.

In regards to the incident yesterday where a tornado passed straight over two experienced chasers highlights the ever increasing competitiveness amongst chasers to perform and get the most tornadoes and the best footage. Yesterday got very close to producing the first fatalities in a storm chase by a tornado! Whatever you do, don't get caught in the rush or you may not live to see another day of tornadoes...

Regards,

Jimmy Deguara

[David C]

That is excellent Jimmy - it is always good to get the first tube out of the way haha - and a wedge at that! Yes, I bet you had memories of May 15 - in that case I think it was the large scale ascent associated with the intense upper trough lagging back a little further than expected.

I must say I was focused on Texas yesterday since I had limited time to follow the action. It sounds as though this storm was HP, so that must have further added to the challenge. Anyway the next several chase days, some significant perhaps prior to the lull you would expect during early May.

[Jimmy Deguara]

For those brave enough (high speed internet connection) here is the video of the tornado as well as storm scale rotation I was hinting about above:

http://australiasevereweather.com/video/movies/2007/colorado_wedge_tornado_2007.wmv

Added to my observations in my first post, I am thinking that I had taken a a photograph but it may have turned out blurry of a possible satellite funnel/tornado. This developed rapidly on the western side of the major circulation. I wished I had been filming at the time. My photographs were not the best at all.

Regards,

Jimmy Deguara

[Jimmy Deguara]

Ok have anyone of you seen the structures achieved on this day - check out my friend's website Gene Rhoden - this is what these large supercells including mine if you look closely looked like close up:

http://www.weatherpix.com/042107.htm

no comparison when it comes to road options though!

I am not sure if people are aware, there were numerous supercells and mesocyclones occurring during this relatively short timeframe - only a relative few actually produced the tornadoes.

To add to my comments earlier the National Weather Service suggested there were farm equipment damaged - something along those lines in relation to the major radar readings / tornado.

Regards,

Jimmy Deguara

[Geoff Thurtell]

Some interesting footage there Jimmy! I wouldn't have liked to be in the middle of that one. Fortunate that it was just over farmland. If it had passed through a town we would be hearing of more than just farm equipment damage. Let us know what the final verdict is from the NWS.
Regards,
Geoff

[Michael Bath]

Jimmy's photos for 21st April:

http://australiasevereweather.com/photography/photos/2007/jd20070421.html

Great stuff intercepting this  
slowly catching up on what has been going on here and the US since the holiday in Tasmania ...

[David C]

Checked out the video last night and certainly that is a very intense circulation Jimmy and very large tornado - awesome - just a shame it was Hp and hence limited opportunities to shoot high contrast footage (and no opportunity to shoot tripoded footage!).

Today (day) was somewhat of a dud. In saying that there were some nice storms, and even a few tornadoes in southern Kansas and possibly further west in Colorado. Overall, this was to be expected  given that the upper level support was back west, and in fact the (was) Caprock Lp (stormtrack) looks like it  encountered some subsidence in the mid-levels. In addition, the subtropical jet has transported a thick cirrus layer which has also largely limited insolation. Further north, however,  things are now hotting up near Goodland (KS)

All eyes will now be on the passage of this approaching upper level low which begin to help along the Colorado storms during the night, as large scale acent increases, and will set the stage for tomorrow. Tomorrow looks fairly complex with respect to ongoing / early convection although these systems do produce tornadoes, whatever the time of day.

[Jimmy Deguara]

Yes David,

There were a couple of issues yersterday. Even though I targeted north east Texas Panhandle and would have got the tornadoes near Woodward, I chose to stay with the dryline. Unfortunately, it decided to retreat a little and this eased any dryline convergence required to create magic. There was not doubt that the LP supercell spun like a top! Unbelievable. And yes it was tornado warned and had aminor region of rapid rotation and slot.

You are correct though - I could immediately see the mid level depletion of the LP supercell. Prior to this cell though was another few cells that showed good signs of organising with beaver tail etc. Unfortunately, the storm went down hill from here. Nice picturesque LP though - barber pole.

Regards,

Jimmy Deguara

[Jimmy Deguara]

Hi,

Be careful with these high risk events as they often only produce squall lines - weak cap etc. There were tornadoes yesterday but not many at all. Most tornadoes occurred in Kansas.

All storms were looking crap to the north although one became tornado warned. Storms simply struggled to even remotely organise. We then looked just to our south and noted one slightly better organised. When approaching this cell (NW of Hutchison), we noted the cell was better structured. Was that a beaver tail and cow catcher? There was hardly an anvil overhead. Then we saw an exploding pulse all captured on video timelapse. Of course I look WSW and thought is that a clear slot? Yes it had even a small area of rotation and yes - this LP low topped supercell was spinning like a top andwas now sending down a funnel cloud. The funnel develops on several occasions and does not succeed. Whilst we moved to our new location - a puff of dust occurs! We quickly set up as this same funnel tornadoes a few times. It was absolutely awesome! We were only half a mile away and watched the circulation now moving ENE near us to our north and the tornado touches down once or twice with a nice green field. A white funnel added to the beauty and the rotation being so close was amazing!

We followed this tornado a little further and got a nice serpantine funnel around the main tornadic funnel under the same mesocyclone! At this point the mesocyclone lower showing quite strong rotation. Eventually, the storm produced a second mesocyclone and thence dropped another brief dust tornado.

What amazed me is we were near the storm prior to it dropping the tornado or being tornado warned even and once the tornado warning came on, there was a mass of chasers coming from all around. It was a traffic jam! Anyway, the storm eventually got undercut by the boundary- the triple point was not able to maintain for long enough - anyone who was not in the vicinity would have missed the event!

Tim Marshall, I and the rest of the group once again an joined together for a steak at Wichita! And boy the steak went down well!

The count for me now is 3 tornadoes from two totally different environmental chases or storm types for that matter.

By the way, to gibe a general perspective of the distance travelled, we did 850miles yesterday and arrived back at 3:30am given Tim had to work today! The distance covered say by the general high risk to the top of the moderate risk would cover a north south path of about 14 hours drive! Think about the thousands of square kilometres this covers! And there were only a handful of tornado reports.

In relation to this low topped supercell, there were reports on stormtrack of multiple tornadoes (as much as 10) from this storm where really there were only two! Two mesocyclones - two tornadoes from these mesocyclones. The first mesocyclone had multiple touchdowns but it is only counted as one tornado. The second could not be mistaken - it was a brief dustwhirl in the field only 100 to 200metres away.

Regards,

Jimmy Deguara